Volkswagen Workshop Service and Repair Manuals

Special tools, workshop equipment, testers, measuring instruments and auxiliary items required

• ◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715
• ◆ Fault reader V.A.G 1551 (or vehicle system tester V.A.G 1552) with cable V.A.G 1551/3
• ◆ Adapter set V.A.G 1594
• ◆ Test box V.A.G 1598/31
• ◆ Current flow diagram

Check conditions

• ● → Fuse No. 36 must be OK.
• ● The battery voltage must be at least 11.5 V.
• ● All electrical consumers, e.g. lights and rear window heating must be switched off.
• ● If the vehicle is equipped with an air conditioning system, this must be switched off.
• ● No faults must be stored in fault memory , interrogating and erasing fault memory.
• ● Speedometer must be OK., checking speedometer:

=> Electrical system; Repair group 90

Test sequence

Note:

To check the speed signal the vehicle must be driven. To do this a second person is necessary.

Observe the valid safety precautions when carrying out a road test => Page 24-28 .

• ‒ Connect fault reader V.A.G 1551 (V.A.G 1552). Start engine and select "Address word" 01 of engine control unit. When doing this the engine must be running at idling speed.
  (Connecting fault reader and selecting engine control unit => Page 01-10 .)

• ‒ Press keys 0 and 8 for the function "Read measured value block" and confirm entry with Q key.

• ‒ Press keys 0, 0 and 5 for "Display group number 5" and confirm entry with Q key.

• ‒ Carry out test drive with a 2nd person to observe display.
• ‒ Observe figure displayed in display zone 3:
       Specification: approx. driven speed
• ‒ Drive slower. The displayed value must
       decrease.
• ‒ Press the ⇒key.
• ‒ Press keys 0 and 6 for the "End output" function and confirm input with the Q key.
• ‒ Switch off ignition.

If no speed is indicated or the display values reduce when driving slowly:

• ‒ → Connect test box V.A.G 1598/31 to control unit wiring harness. The engine control unit remains disconnected.
• ‒ Connect multimeter to measure voltage between test box sockets 3 (terminal 15) + 9 (vehicle speed signal).
• ‒ Raise front left side of vehicle.
• ‒ Switch on ignition.
• ‒ Rotate front wheel and observe voltage display.
       Specification: 0.0...at least 4.0 Volt fluctuating

Note:

If necessary, hold the front right wheel to prevent it from turning.

If the display does not fluctuate:

• ‒ Check wiring from test box socket 9 to dash panel insert for open or short circuit referring to current flow diagram:

=> Current flow diagrams, Electrical fault finding and Fitting locations